AdvertisementAstronomers Map Dark Matter 'Beach Ball'January 07, 2010Nell GreenfieldboycefacebookEmailA view of the central region of the Milky Way galaxy. Dark matter accounts for more than 70 percent of the mass of the Milky Way, but because dark matter is invisible, all we see when we look up in the sky is a small amount of stars, planets and gas. (AP/NASA)